Homeless youth are a vulnerable and understudied group who has consistently reported elevated levels of substance use. Understanding the factors associated with substance use within this population may help guide future intervention efforts. Although few studies have examined the role of abstinence selfefficacy and coping in substance use among homeless youth, some research indicates that higher abstinence self-efficacy and greater use of task-oriented coping are related to lower substance use, while greater use of emotion-oriented and avoidance-oriented coping are related to higher substance use. Accordingly, the current study examined the relationship between abstinence self-efficacy, coping, and substance use among homeless youth, while controlling for the effects of age, gender, and ethnicity. A sample of 40 homeless youth (ages 17 to 24) was recruited from the only drop-in center in a Midwestern city. Data were obtained at one point in time, and included information regarding abstinence self-efficacy, coping, and frequency of alcohol and drug use. A series of hierarchical regression analyses were conducted. In order to control for the effects of age, gender, and ethnicity, these variables were entered in the first step, and abstinence self-efficacy and coping were included in the second step of analysis. A significant relationship was found between abstinence self-efficacy and alcohol and drug use. Specifically, higher abstinence self-efficacy was related to lower alcohol and drug use. Additionally, an interaction between abstinence self-iiiefficacy and substance use was found in which African American, compared to nonAfrican-American youth, reported reduced alcohol use as their level of abstinence self-efficacy in social pressure to use increased. However, coping was not associated with substance use. The current study provides empirical support for the relationship between abstinence self-efficacy and substance use among homeless youth. The findings have practical implications. Although a longitudinal design and an intervention trial is needed to confirm, increasing abstinence self-efficacy through intervention efforts may be an effective strategy for reducing substance use among these youth.